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Using Metal Cutting Processes and

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Title: Using Metal Cutting Processes and


1
Lesson 5
  • Using Metal Cutting Processes and
  • Techniques

2
Next Generation Science/Common Core Standards
Addressed!
  • CCSS.EL A Literacy.RST.9-10.1 Cite specific
    textual evidence to support analysis of science
    and technical texts, attending to the precise
    details of explanations or descriptions.
  • CCSS.ELA Literacy. RST.9-10.3 Follow precisely a
    complex multistep procedure when carrying out
    experiments, taking measurements, or performing
    technical tasks, attending to special cases or
    exceptions defined in the text.
  • CCSS.ELA Literacy.RST.11-12.1 Cite specific
    textual evidence to support analysis of science
    and technical texts, attending to important
    distinctions the author makes and to any gaps or
    inconsistencies in the account.
  • CCSS.ELA Literacy.RST.11-12.3 Follow precisely a
    complex multistep procedure when carrying out
    experiments, taking measurements, or performing
    technical tasks analyze the specific results
    based on explanations in the text

3
Bell Work/Student Learning Objectives
  • 1. Identify the equipment used when cutting cold
    metal.
  • 2. Describe the processes and techniques used
    when cutting cold metal.
  • 3. Identify the equipment used when cutting hot
    metal.
  • 4. Describe the processes and techniques used
    when cutting hot metal.
  • 5. Identify safety practices that should be
    observed when cutting cold and hot metal.

4
Terms
  • Cape chisels
  • Diamond point chisels
  • Double cut file
  • File
  • Flat chisels
  • Hacksaw
  • Rasp
  • Round nose chisels
  • Single cut file
  • Snips or shears

5
Interest Approach
  • There are 2 pieces of metal that are the same
    size and thickness in the ag. mechanics lab.
  • Student 1 will be using a hacksaw to cut the
    piece of metal.
  • Student 2 will be using a gas torch to cut the
    piece of metal.
  • Will there be any differences?
  • Advantages/disadvantages?

6
What equipment is used when cutting cold metal?
7
Cold Metal Cutting
  • Cold metal may be cut with a hacksaw, cut-off
    saw, band saw, bolt cutter, file, snips or
    shears, or a cold chisel.

8
Cold Metal Cutting
  • Cold metal cutting tools are divided into
    categories depending on their power source,
    either hand or power.
  • The operator provides the power for operating the
    hand tools, while power tools rely on a source
    other than the operator for power.

9
Hacksaw
  • A tool often used for cutting metal is the
    hacksaw.
  • A hacksaw is a saw with a frame and a blade
    designed for cutting metal.
  • They are designed so new blades can be installed
    easily.

10
Hacksaw
  • Select the proper blade for the job to be
    completed.
  • Hacksaw blades vary in type and size.
  • All-hard blades are hardened throughout and are
    used for sawing heavy work, tool steel, cast
    iron, and brass.

11
Hacksaw
  • Only the teeth are hardened on the flexible
    blades. They are used for sawing light and hollow
    materials.
  • Hand hacksaw blades are made in 8 inch, 10 inch
    and 12 inch lengths, with 14, 18, 24, or 32 teeth
    per inch.

12
Hacksaw
  • Hacksaw blades can be purchased with an undulated
    (wavy), alternate, or raker tooth arrangement
    pattern.
  • Lower quality blades have undulated teeth
    arrangement.

13
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14
Bolt cutters
  • Bolt cutters provide a fast and efficient method
    of cutting bolts, rods, and other small metals.
  • The capacity of the bolt cutter is stamped on
    ranges from 3 /16 inch to ¾ inch.

15
Files
  • A file is made of hardened high-carbon steel,
    with flat or rounded surfaces that are made rough
    with teeth or grit.
  • They are used for smoothing surfaces or
    sharpening metal objects.

16
Files
  • Files come in various shapes and sizes and in
    various sizes of cuts (chisel teeth).
  • A file with straight teeth all going in the same
    direction is a single cut file.
  • A file with teeth in two directions is known as a
    double cut file.

17
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18
Parts of a File
19
Files
  • A file with sharp pointed teeth is known as a
    rasp.
  • Both single cut and double cut files are made in
    different degrees of coarseness.
  • Rough, middle, bastard, second cut, and smooth
    are examples of coarseness.
  • The coarseness also varies with the length of the
    file.

20
Cuts of a File
21
Files
  • Common files are flat, rasp, half round, round
    bastard, and taper triangular.
  • Flat files are used for smoothing both wood and
    metal.
  • Rasp cut files are used for smoothing coarse wood
    work.
  • Half round files are used for both metal and wood.

22
Files
  • Round bastard files are used for enlarging and
    smoothing holes.
  • Taper triangular files are used for filing saws
    or cleaning threads.

23
Shapes of a File
24
Care of a File
25
Snips or shears
  • Snips or shears are large scissor-like tools for
    cutting sheet metal and fabrics, and are divided
    into regular, or compound aviation.
  • Regular snips or shears are used for light
    cutting, while compound or aviation are used for
    heavy cutting.
  • Snips or shears are used for cutting straight,
    left-hand, or right-hand curves.

26
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27
Cold Chisels
  • When using a cold chisel to cut metal, the chisel
    must be harder than the metal it is intended to
    cut.
  • The four standard shapes for cutting edges for
    cold chisels are flat, cape, diamond-point, and
    half-round nose.

28
Cold Chisels
  • 1. Flat chisels are used for chipping, removing
    metal from a flat surface, and cutting sheet
    metal.

29
Cold Chisels
  • 2. Cape chisels are used for cutting narrow, flat
    grooves and slots.

30
Cold Chisels
  • 3. Round nose chisels are used to cut concave
    grooves.

31
Cold Chisels
  • 4. Diamond point chisels are used to cut v-shaped
    grooves.

32
Cold Chisels
  • 1. Flat chisels are used for chipping, removing
    metal from a flat surface, and cutting sheet
    metal.
  • 2. Cape chisels are used for cutting narrow, flat
    grooves and slots.
  • 3. Round nose chisels are used to cut concave
    grooves.
  • 4. Diamond point chisels are used to cut v-shaped
    grooves.

33
F. Metal cutting power tools are reciprocating
hacksaws, band saws, cut-off saws, and shears.
34
The Power Hacksaw
  • The power hacksaw has a reciprocating movement
    which operates similar to the hand hacksaw,
    however it cuts much faster.
  • The frame holds a rigid blade which is ¾ inch to
    1 inch wide and 12 inches to 18 inches long.
  • Blades are available with fine to coarse teeth.

35
Horizontal Band Saws
  • Horizontal band saws have a blade that travels on
    wheels and moves through rollers and guides, and
    saws parallel to the ground.
  • Blade movement is forward at all times, so it
    cuts continuously, which results in faster
    cutting than the power hacksaw.

36
Metal Cut-off Saws
  • Metal cut-off saws, also known as chop saws, use
    a circular blade lowered into the material that
    is being cut.
  • The cutting blade is an abrasive disc that
    provides a straight clean cut.

37
The Power Shear
  • The power shear can cut flat, angle, and other
    structural steel faster and cleaner than by hand
    or by power saw.

38
What processes and techniques are used when
cutting cold metal?
39
Hacksaws are made to cut metal.
  • 1. Be sure safety glasses are worn.
  • 2. Select a blade with enough teeth per inch so
    that two or three teeth are in contact with the
    metal at all times.
  • There must be few enough teeth to the inch to
    allow the gullets to carry off the chips without
    clogging.

40
Hacksaws
  • 3. Fasten the blade into the hacksaw frame with
    the teeth pointing away from the handle of the
    saw.
  • Make sure the blade is fastened securely so that
    it will not twist and break.

41
Installing a Hacksaw Blade
42
Installing a Hacksaw Blade
43
Hacksaws
  • 4. Mark the stock at the point at which it is to
    be cut.
  • 5. Place the stock in the vise, with the mark
    about ½ inch from the jaws.
  • Sawing close to the jaws of the vice makes the
    sawing easier because the piece is held firmly
    and does not spring back and forth.

44
Hacksaws
  • 6. Place the saw on the mark and then pull it
    toward you using little pressure to start the
    kerf.
  • To help get the saw started in the proper place,
    a notch can be cut at the mark with a file.

45
Hacksaws
  • 7. Apply slight pressure on the forward strokes
    of the hacksaw, and release the pressure on the
    return strokes to insure proper cutting and to
    lessen the danger of breaking the blade of the
    saw.

46
Hacksaws
  • 8. Run the saw evenly, using long strokes, with
    all the teeth cutting to prevent wear on a small
    portion of the blade, thus shortening the life of
    the blade.

47
Hacksaws
  • 9. Thin metal can be cut more easily with a
    hacksaw if a thin piece of wood is clamped on
    each side of the metal.
  • Saw through the metal and wood pieces
    simultaneously.

48
Similar procedures should be followed when using
a horizontal band saw.
49
Chisels
  • Chisels are made to cut cold metal. These will
    usually cut any metal which can be filed.
  • 1. Be sure safety glasses are worn.
  • 2. Mark the material to be chiseled.
  • 3. Select the correct chisel for the job.
  • Make sure the edge is in good condition.

50
Chisels
  • 4. Place the stock in a vise or clamp it to the
    table. Watch the edge of the chisel as you work.
  • 5. Sharp, quick blows are best. Reset the chisel
    after each blow.
  • 6. The angle of the cutting edge of a chisel
    should be approximately 65 degrees with the
    cutting edge slightly rounded.

51
Chisels
  • 7. In removing metal, hold the chisel at an angle
    that will keep the surface of the work and the
    lower bevel of the chisel parallel.
  • 8. When cutting heavy, round stock, cut halfway
    through, then turn the stock and make the rest of
    the cut from the opposite side.

52
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53
Files
  • Small amounts of metal may be removed where
    needed with a file.
  • 1. Be sure safety glasses are worn.
  • 2. Mark the material to be filed.
  • 3. Place the stock in a vise or clamp it to the
    table.
  • 4. Select the correct file for the job to be
    done.

54
Files
  • 5. File teeth usually slant toward the point of
    the file and therefore cut only on the forward
    stroke.
  • 6. A handle should be placed on the tang of the
    file.
  • 7. Hold the handle of the file against the palm
    of the hand, with the thumb on the top of the
    handle.

55
Files
  • 8. Hold the point of the file with the thumb and
    index finger of the other hand.
  • 9. Use pressure on the forward stroke only, and
    use only enough pressure to make the file cut
    evenly.
  • Do not bear down hard on a new file, or the teeth
    will be ruined.
  • A new file should be broken in by using it first
    on brass or bronze.

56
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57
Files
  • 10. Lift the file on the return stroke when using
    s single cut file. A double cut file will cut in
    both directions.
  • 11. Do not take more than 30 to 40 strokes a
    minute.
  • Excessive speeds will ruin both the file and the
    work.

58
Files
  • 12. Rubbing chalk on a file before it is used
    will help to prevent it from becoming clogged.
  • If a file becomes clogged, it may be cleaned with
    a file card, pick, and brush.

59
Files
  • 13. Do not use a file on material harder than the
    file.
  • 14. Store files in separate holders to prevent
    their rubbing together or knocking against other
    tools.
  • The teeth are brittle and thus are easily dulled
    or broken.

60
Snips or shears
  • Snips or shears are used for cutting sheet metal
    and fabrics.
  • 1. Be sure safety glasses are worn.
  • 2. Mark the material to be filed.
  • 3. Place the stock in a vise or clamp it to the
    table.
  • 4. It is advisable to wear gloves when handling
    and working with sheet metal.

61
Snips or shears
  • 5. Select the correct shears for the job to be
    done.
  • Select a pair of shears that are sharp and free
    of nicks.
  • 6. A piece of scrap should be cut first to be
    sure the shears are heavy enough.

62
Snips or shears
  • 7. Shears are used like scissors.
  • For them to work well, the metal must curl or
    lift up and out of the shear as the cut
    progresses.

63
Cutoff saws
  • Cutoff saws are the most common method of cutting
    steel in Agriculture Mechanics classes.
  • 1. Be sure safety glasses are worn. Hearing
    protection may also be needed.
  • 2. Mark the material to be cut.

64
Cutoff saws
  • 3. Be sure the saw is properly adjusted and the
    blade in the machine is designed to cut the kind
    of material to be cut.
  • 4. Place the stock on the table of the saw and
    use the vise or clamp to hold it securely.

65
Cutoff saws
  • 5. Hold the handle with one hand and turn the
    switch on.
  • 6. Lower the saw slowly into and through the
    material to be cut using a slow deliberate
    motion.

66
Cutoff saws
  • 7. After the cut is made, let the saw rise, and
    turn off the switch.
  • 8. After the saw has stopped turning, release the
    handle and remove the material.

67
The Power Hacksaw
  • The power hacksaw is very useful in the
    agricultural mechanics shop.
  • 1. Be sure safety glasses are worn.
  • 2. Mark the material to be filed.
  • 3. Be sure the saw is properly adjusted and the
    blade in the machine is designed to cut the kind
    of material to be cut.

68
The Power Hacksaw
  • 4. Place the frame in the raised position.
  • 5. Adjust the vise on the machine to hold the
    metal at the desired angle.
  • 6. Position the metal in the vise on the machine
    and tighten securely.

69
The Power Hacksaw
  • 7. Turn on the machine.
  • 8. Lower the frame slowly and carefully until the
    blade is on the stock and starting to cut.
  • 9. If equipped with coolant, turn it on during
    the duration of the cut.
  • 10. Stay near the machine while it is cutting.

70
The Power Hacksaw
  • 11. Switch off the machine when the cut is
    finished if it does not turn off automatically.
  • 12. Remove all scrap metal and clean up all metal
    dust and coolant.

71
What equipment is used when cutting hot metal?
72
Hot cutting is most often performed with an
oxy-fuel gas torch, or plasma cutter.
73
Fuel gas welding
  • 3. When oxygen strikes a preheated metal surface,
    it causes the metal to burn or oxidize.
  • The oxygen combines with the heated iron to form
    a molten metal and slag which flows or is blown
    away, exposing more metal to the oxygen jet.

74
Fuel gas welding
  • 4. The tip of a cutting blowpipe has several
    small holes (orifice) located around a larger
    hole in the center of the tip.
  • The small holes permit the oxyacetylene mixture
    to pass through them.
  • They provide flames to preheat the metal before
    it is cut.

75
Fuel gas welding
  • The large hole in the middle of the tip supplies
    a jet of oxygen under high pressure that does the
    actual cutting after the metal is preheated to a
    red heat.

76
The arc welding electrode
  • The arc welding electrode can be used for cutting
    metal.
  • An electrode is useful for cutting cast iron, for
    cutting in inaccessible places, and for cutting
    small jobs.

77
The arc welding electrode
  • The use of an arc is usually considered to be the
    best method of cutting cast iron, because cast
    iron does not oxidize with heat.
  • To be cut, cast iron must be melted and the
    electric arc melts metal as a means of cutting it.

78
The arc welding electrode
  • Cutting metal with an electrode is fast, but the
    cut is not smooth.
  • Steel melts at approximately 2,600F, while the
    heat generated by the electric arc is 6,500F.

79
Plasma arc cutters
  • Plasma arc cutters work by sending an electric
    arc through a gas that is passing through a
    constricted opening.
  • The gas can be shop air, nitrogen, argon, oxygen,
    etc.
  • This elevates the temperature of the gas to the
    point it enters a fourth state of matter, plasma.

80
Plasma arc cutters
  • 1. As the metal being cut is part of the circuit,
    the electrical conductivity of the plasma causes
    the arc to transfer to the work.
  • 2. The restricted opening or nozzle the gas
    passes through causes it to squeeze by at a high
    speed.
  • The high speed gas actually cuts through the
    molten metal.

81
Plasma arc cutters
  • The gas is also directed around the perimeter of
    the cutting area to shield the cut.
  • 3. Plasma cutters are ideal for cutting mild and
    stainless steel, aluminum, brass and copper.
  • Virtually no heat spread is given.
  • This means almost no distortion or discoloration
    occurs to the material being cut.

82
Plasma arc cutters
  • 4. Computer numerically controlled (CNC) plasma
    cutters fully automate the shape production
    process.
  • These machines can be relatively inexpensive
    units that operate by personal computers.
  • Those used with expensive, limited production
    computers made specifically for running the
    burning machines may cost as much as 100,000.

83
Fuel Gas Cutting Procedure
  • Place the piece of steel on the welding table so
    that the mark clears the edge of the table by at
    least one inch. This should eliminate damaging
    the table surface.

84
Fuel Gas Cutting Procedure
  • Be sure safety glasses are worn. Put on a gas
    welding face shield or goggles, and gloves.
  • Light the cutting blowpipe.

85
Fuel Gas Cutting Procedure
  • Follow the same procedures for lighting,
    adjusting, and shutting down the blowpipe that
    were given in the previous lessons.
  • An addition to the lighting procedure is to
    depress the cutting-oxygen valve lever and check
    to see that a neutral flame is present.
  • If necessary, adjust the pre-heat oxygen valve
    until a neutral flame is maintained when the
    cutting-oxygen valve is open.

86
Fuel Gas Cutting Procedure
  • Hold the blowpipe with the nozzle perpendicular
    to the surface of the metal and with the inner
    cones of the preheating flames at the edge of the
    piece of steel and about 1 /16 inch above the
    chalk line.

87
Fuel Gas Cutting Procedure
  • Hold the blowpipe steady at this spot until the
    steel becomes a bright red, then slowly press
    down the cutting-oxygen valve lever. When the
    metal has been pierced tilt the torch so that the
    tip is pointing in the direction of travel and
    begin to move slowly.
  • A bright red color indicates that the steel is
    near the melting point.
  • Move the blowpipe slowly along the cut-off line,
    cutting completely through the metal as the
    cutting proceeds.

88
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89
Arc Welding cutting Procedure
  • Cutting with the arc welding electrode requires
    the use of 30 percent more amperage than would be
    used for welding.
  • Be sure safety glasses are worn.
  • Put on a electric welding face shield and gloves.

90
Arc Welding cutting Procedure
  • When cutting flat metal which is thicker than the
    electrode, the metal to be cut is placed in a
    flat or horizontal position.
  • Strike the arc where the cut is to be made, and
    allow the heat of the arc to form a crater of
    molten metal.

91
Arc Welding cutting Procedure
  • Move the electrode back and forth in a sawing
    motion to force the molten metal from the cut or
    kerf.

92
Arc Welding cutting Procedure
  • A downward pushing motion coupled with a quick
    upward motion helps to force the molten metal
    from the cut.
  • Since arc cutting is done by melting the metal,
    the motion of the electrode and the position of
    the work should assist the molten metal to fall
    out of the cut.

93
Arc Welding cutting Procedure
  • When cutting round stock, start at an outer edge
    of the stock so that the molten metal can escape.
  • Follow the same procedures as when cutting flat
    stock.
  • When the cut reaches the center of round stock, a
    new cut is made from the opposite side.

94
Arc Welding cutting Procedure
  • In cutting holes, burn a hole by pushing the
    electrode through the metal.
  • Use a short arc and push the tip of the electrode
    into the crater of molten metal.
  • If a larger hole is needed than the hole burned
    by the electrode, move the electrode around the
    edge of the hole in a widening circle until a
    hole of the desired size is obtained.

95
Plasma Cutting Procedure
  • A plasma cutter is operated very similar to the
    oxyacetylene torch in that the tip does not touch
    the workpiece.

96
Plasma Cutting Procedure
  • 1. Be sure safety glasses are worn.
  • 2. Turn the machine on and set it to
    manufacturers recommendations.
  • 3. Put on an electric welding face shield and
    gloves.

97
Plasma Cutting Procedure
  • 4. Hold the plasma arc gun with the contact tip
    perpendicular to the surface of the metal at the
    edge of the piece of steel and no closer than 1
    /16 inch above the cut-off line.

98
Plasma Cutting Procedure
  • 5. Depress the trigger on the gun and move slowly
    along the cut-off line, cutting completely
    through the metal as the cutting proceeds.
  • 6. When the cut is complete let loose of the
    trigger to extinguish the arc.

99
What safety practices are observed when cutting
cold and hot metal?
100
V. When cutting cold and hot metal, observe the
following safety practices. Obtain the
instructors permission before using any tool or
machine. Follow these guidelines
101
Safety Guidelines
  • A. Keep the work area and tools clean.
  • Dirty, greasy, and oily tools and floors can
    cause accidents.
  • Clean and put away all unneeded tools and
    materials.
  • Clean up oil spills and scrap metal from the
    floor and equipment.
  • Keep paths to exits clear.

102
Safety Guidelines
  • B. Wear industrial quality eye protection to
    protect eyes from sparks and metal chips.
  • C. To protect against burns, wear clothing such
    as coveralls, high-top shoes, leather aprons, and
    leather gloves.
  • Remove all paper from pockets, and wear cuffless
    pants.

103
Safety Guidelines
  • D. Protect hair and scalp by restraining long
    hair and wearing a cap.
  • E. Loud talking as well as pushing, running, and
    scuffling while working with hot metal can cause
    serious accidents.
  • Keep your mind on your work!

104
Safety Guidelines
  • F. In the event of an emergency, all students
    involved in or observing the emergency should
    call for help immediately.
  • You should know the location of fire
    extinguishers and fire blankets and how to use
    them.
  • You should also know the approved procedure for
    exiting the laboratory.

105
Safety Guidelines
  • G. Report all injuries or accidents to the
    instructor immediately, no matter how slight.
  • H. Always use the right size tool and only for
    its intended purpose.
  • I. Be certain that stock to be worked is securely
    fastened in a vise or by clamps to prevent tools
    from slipping.

106
Safety Guidelines
  • J. Mount vises, anvils, and clamps securely for
    metalwork.
  • K. Work in a well-ventilated area. Fumes and
    intense heat are a part of hot metalwork and
    require that work be done outdoors or in a
    forced-ventilated area.

107
Safety Guidelines
  • L. When lifting heavy objects, obtain help.
  • Lift with the legs and not the back.
  • Straining to lift heavy objects can cause serious
    injury.

108
Safety Guidelines
  • M. To avoid the possibility of accidental burns,
    keep hot metal in a safe place until it cools.
  • Test metal with moistened finger tips before
    actually touching it.
  • Use tongs or pliers for handling hot metal.

109
Safety Guidelines
  • N. Before leaving the laboratory or work station,
    make certain the heat source is shut off and
    cool.
  • O. Do not perform hot metalwork on wood
    floors/tablers or near flammable materials.
  • Never work on containers that have been used for
    storage of combustible material.

110
Safety Guidelines
  • P. Keep cables and hoses from coming in contact
    with hot metal and sharp objects.
  • Never point a flame at cables or hoses.

111
Review/Summary
  • 1. Identify the equipment used when cutting cold
    metal.
  • 2. Describe the processes and techniques used
    when cutting cold metal.
  • 3. Identify the equipment used when cutting hot
    metal.

112
Review/Summary
  • 4. Describe the processes and techniques used
    when cutting hot metal.
  • 5. Identify safety practices that should be
    observed when cutting cold and hot metal.

113
The End!
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